1. Field of the Invention
The present invention relates to an organic light-emitting display (OLED) and method of manufacturing the same and, more particularly, to an active matrix OLED and method of manufacturing the same.
2. Discussion of the Related Art
An (OLED) is an emissive display device that electrically excites fluorescent organic compounds to emit light. OLEDs are either passive-matrix type or active-matrix type, depending upon the method utilized to drive the display pixels, which are arranged in a matrix. The active-matrix OLED consumes less power than the passive-matrix OLED, thus providing the capability to create a larger display area at a higher resolution.
FIG. 1 shows a cross-sectional view of a conventional passive-matrix OLED and a method for manufacturing the same.
Referring to FIG. 1, a buffer layer 105 is formed on an insulating substrate 100. Utilizing a conventional method, a driving thin film transistor (TFT) is then formed on buffer layer 105 by sequentially forming an active layer 110, a gate insulating layer 120, a gate electrode 130, an interlayer 140, and source/drain electrodes 145. A planarization layer 155 is formed on the entire surface of the substrate, which includes the driving TFT. A via hole 150 is then formed in the planarization layer 155 to expose any one of the source/drain electrodes 145.
A pixel electrode 170 is then formed within the via hole 150 to contact the exposed source/drain electrodes 145. Since the pixel electrode 170 is formed along the bottom and side wall of the via hole 150, it has a recessed region in the via hole 150.
A pixel defining layer 175, formed to cover pixel electrode 170, has an opening 178 spaced from the via hole 150, at a predetermined distance, in order to expose pixel electrode 170. An organic emission layer 180 is formed on the pixel electrode 170, exposed by the opening 178, and an opposite electrode 190 is formed on the organic emission layer 180, thereby forming an organic light-emitting diode. This organic light-emitting diode is connected to, and driven by, the driving TFT through the via hole 150.
With this method of manufacturing an OLED, the pixel defining layer 175 is formed to cover the pixel electrode 170 recessed in the via hole 150. Here, the pixel defining is layer 175 has an opening 178 spaced from the via hole 150 at a predetermined distance. The organic emission layer 180 is not located over the recessed portion of pixel electrode 170 in order to prevent recession and deterioration of the organic emission layer 180. However, because the opening 178 is formed and spaced from the via hole 150 at a predetermined distance, an opening area (P), which is defined by the opening 178, is limited, and the resultant aperture ratio of the opening area (P) to the unit pixel area is also limited. These limitations are greater in a top-emitting OLED, which emits light from organic emission layer 180 in a direction away from the substrate 100.